Richard Sipe, a leading expert on celibacy and clerical sexual abuse, died in California on 8 August aged 85. A former Benedictine priest and psychotherapist, he had investigated and written on the sexual abuse crisis in the Church for four decades.

In 1990 he published his landmark book, A Secret World: Sexuality and the Search for Celibacy. Based on interviews with 1,500 priests and others with first-hand knowledge of celibacy violations, Mr Sipe estimated that six per cent of all priests were having sex with children and young people.

He warned that sexual abuse of children by Catholic priests was a systemic problem within the Church fostered by the culture of celibacy, secrecy and hypocrisy. He suggested that only about half of the priests in the United States were at any one time practising celibacy – an estimate the Church said was exaggerated.

Accusations against McCarrick had been documented by Mr Sipe for years. He supported hundreds of survivors through counselling and as an expert witness in court cases. In a letter to Bishop Robert W. McElroy of San Diego in 2016, he wrote: “When men in authority – cardinals, bishops, rectors, abbots, confessors, professors – are having or have had an unacknowledged-secret-active-sex life under the guise of celibacy, an atmosphere of tolerance of behaviours within the system is made operative.”